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The effect of stimulus distribution form on the acquisition and rate of conditioned responding: Implications for theory

Lookup NU author(s): Dr Domhnall Jennings



In four experiments rats were conditioned to an auditory conditioned stimulus (CS) that was paired with food, and learning about the CS was compared across two conditions in which the mean duration of the CS was equated. In one the CS was of a single, fixed duration on every trial, while in the other the CS duration was drawn from an exponential distribution, and hence changed from trial to trial. Higher rates of conditioned responding to the fixed than to the variable stimulus were observed, in both between- (Experiment 1) and within-subject designs (Experiments 2 and 3). Moreover, this difference was maintained when stimuli trained with fixed or variable durations were tested under identical conditions (i.e. with equal numbers of fixed and variable duration trials) - suggesting that the difference could not be attributed to performance effects (Experiment 3). In order to estimate the speed of acquisition of conditioned responding, the scaled cumulative distribution of a Weibull function was fitted to the trial-by-trial response rates for each rat. In the within-subject experiments specific differences in the pattern of acquisition to fixed and variable CS were shown; a somewhat different pattern was found when ITI was manipulated (Experiment 4). The implications of these findings for theories of conditioning and timing are discussed. Normal 0 false false false EN-GB JA X-NONE

Publication metadata

Author(s): Jennings DJ, Alonso E, Mondragon E, Franssen M, Bonardi C

Publication type: Article

Publication status: Published

Journal: Journal of Experimental Psychology: Animal Behavior Processes

Year: 2013

Volume: 39

Issue: 3

Pages: 233-248

Print publication date: 01/07/2013

Date deposited: 04/02/2013

ISSN (print): 0097-7403

ISSN (electronic): 1939-2184

Publisher: American Psychological Association


DOI: 10.1037/a0032151


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